Where Vercel is the better pick
Vercel isn’t a worse product, it’s a different job. If you’re a developer shipping a real application from a Git repo, with serverless functions, preview deployments per pull request, environment variables and a CI pipeline, Vercel is superb and SiteViewer doesn’t try to replace it. SiteViewer wins when you’re a designer or non-developer who just needs a finished HTML design in front of a client, privately, on your own domain, without going anywhere near a terminal.